高分英文物理题Ahorseinaharnessracingstartstoracepullingacarriagewithajockeyinit.Thehorseexertsabackwardforceof2800Nonthegroundasittakesoff.Themassofthejockeyis110lbs,themassofthecarriageis275lbs

Question

高分 英文物理题
A horse in a harness racing starts to race pulling a carriage with a jockey in it. The horse exerts a backward force of 2800 N on the ground as it takes off. The mass of the jockey is 110 lbs, the mass of the carriage is 275 lbs, and the mass of the horse is 1100 lbs. If we set the direction of the motion of the horse to be the +x direction,
(a) What are the direction and the magnitude of the reaction force by the ground?
(b) What acceleration is produced, assuming the friction between the carriage and the ground is negligible?
(c) Calculate the force the horse exerts on the carriage.
(d) Calculate the force the carriage exerts on the jockey.

Answer 1

我相信首要问题是翻译,如下：
一匹马戴着马具,拉一个坐着驾驶员的马车.马在开始起步时,对地面的反向作用力是2800N,驾驶员质量为110磅,马车质量为275磅,马的质量为1100磅.如果我们假设马的运动方向为X的正方向
（1）地面反作用力的大小和方向是怎样的
（2）假设之间地面和马车之间的摩擦可以忽略不计,那么（马以及马车的）加速度是多少?
（3）计算马对马车的力
（4）计算马车对驾驶员的力
解题：
1磅=0.45359237千克,好麻烦,可是不影响
（1）地面反作用力,大小为2800N,方向沿马的运动方向,这样马才会向前走；
（2）加速度就是地面的反作用力产生的,马向后蹬,才会向前走.a=2800/(1485*0.4536)=4.16
（3）马对马车的力就是提供马车和驾驶员加速度的力,即F=ma=385*0.4536
2800/（1485*0.4536）=725N
（4）马车对驾驶员的力为110*0.4536
2800/（1485*0.4536）=207N